On the 2015 St. Patrick's Storm Turbulent State of the Ionosphere: Hints From the Swarm Mission

The scaling features of electron density fluctuations during the St. Patrick's magnetic storm (17 March 2015) are analyzed to try to characterize the possible turbulent nature of the ionosphere during the development of the geomagnetic storm. The electron density values recorded by two of the three satellites of Swarm constellation during a period of 7 days (16–22 March 2015) around the storm peak are analyzed at middle‐ and high‐latitude regions in both hemispheres. The analysis reveals interesting patterns in the scaling properties of electron density fluctuations and a possible explanation for the occurrence of high values of the Rate of change Of the electron Density Index (RODI). Indeed, the obtained results seem to suggest that very high values of RODI, which describes the structuring of the plasma within a fixed time and is used as an ionospheric disturbance index, are correlated with the antipersistent character of electron density fluctuations and with the values around 5/3 of the power spectral density scaling exponent. These features are independent of the different phases of the analyzed geomagnetic storm and seem to support the idea of a fluid and/or magnetohydrodynamic turbulence as the main responsible of the high values of RODI recorded at high latitudes in the auroral and polar cap regions.